The Dallas Morning News: Earthquakes at DFW Airport continued for years after oil and gas wastewater well was shut

The Dallas Morning News: Earthquakes at DFW Airport continued for years after oil and gas wastewater well was shut

“Faults are not like a light switch – you don’t turn off a well and automatically stop triggering earthquakes.” — Heather DeShon, SMU seismologist.

Science journalist Anna Kuchment covered the earthquake research of a team of SMU seismologists led by SMU Associate Professor Heather DeShon and SMU Post-doctoral Researcher Paul Ogwari, who developed a unique method of data analysis that yielded the study results.

The results of the analysis showed that efforts to stop human-caused earthquakes by shutting down wastewater injection wells that serve adjacent oil and gas fields may oversimplify the challenge. The seismologists analyzed a sequence of earthquakes at DFW Airport and found that even though wastewater injection was halted after a year, the earthquakes continued.

The sequence of quakes began in 2008, and wastewater injection was halted in 2009. But earthquakes continued for at least seven more years.

“This tells us that high-volume injection, even if it’s just for a short time, when it’s near a critically stressed fault, can induce long-lasting seismicity,” said Ogwari. The earthquakes may be continuing even now, he said.

By Anna Kuchment
The Dallas Morning News
Earthquakes beneath DFW International Airport continued for seven years after an oil and gas company shut a nearby wastewater injection well that had been linked to the quakes, according to a new study by scientists at Southern Methodist University.

A wastewater well that continues to operate at the northern end of the airport – and which some area residents have said should be closed — was probably not involved in the events and poses little earthquake hazard, the researchers concluded.

“Faults are not like a light switch – you don’t turn off a well and automatically stop triggering earthquakes,” said Heather DeShon, a seismologist at Southern Methodist University and co-author of the paper, in an email.

The earthquakes at DFW Airport started on Halloween 2008, seven weeks after Chesapeake Energy began injecting wastewater into a well at the southern end of the airport. Scientists at SMU and the University of Texas at Austin investigated the quakes at the time and concluded they were most likely associated with the well.

Though Chesapeake shut its well in August 2009, earthquakes continued through at least the end of 2015. The largest, a 3.4-magnitude event, struck three years after the well was closed.

“It’s very surprising that one year of injection could produce earthquakes running for more than seven years,” said Paul Ogwari, the study’s lead author and a post-doctoral researcher at SMU. The paper was published in the Journal of Geophysical Research.

While earthquake magnitudes did not decline, Ogwari said, earthquake rates did: More than 80 percent of quakes in the sequence occurred during the first seven months of seismicity.

The DFW quakes are significant, because they mark the start of an unprecedented surge of earthquakes in North Texas and across the middle of the country.